Global Transcriptional Profiling of Diapause and Climatic Adaptation inDrosophila melanogaster

Abstract

Wild populations of the model organism Drosophila melanogaster experience highly heterogeneous environments over broad geographical ranges as well as over seasonal and annual timescales. Diapause is a primary adaptation to environmental heterogeneity, and in D. melanogaster the propensity to enter diapause varies predictably with latitude and season. Here we performed global transcriptomic profiling of naturally occurring variation in diapause expression elicited by short day photoperiod and moderately low temperature in two tissue types associated with neuroendocrine and endocrine signaling, heads, and ovaries. We show that diapause in D. melanogaster is an actively regulated phenotype at the transcriptional level, suggesting that diapause is not a simple physiological or reproductive quiescence. Differentially expressed genes and pathways are highly distinct in heads and ovaries, demonstrating that the diapause response is not uniform throughout the soma and suggesting that it may be comprised of functional modules associated with specific tissues. Genes downregulated in heads of diapausing flies are significantly enriched for clinally varying single nucleotide polymorphism (SNPs) and seasonally oscillating SNPs, consistent with the hypothesis that diapause is a driving phenotype of climatic adaptation. We also show that chromosome location-based coregulation of gene expression is present in the transcriptional regulation of diapause. Taken together, these results demonstrate that diapause is a complex phenotype actively regulated in multiple tissues, and support the hypothesis that natural variation in diapause propensity underlies adaptation to spatially and temporally varying selective pressures.

An Intronic Polymorphism in couch potato Is Not Distributed Clinally in European Drosophila melanogaster Populations nor Does It Affect Diapause Inducibility

“…Alternatively it might only be expressed in a small subset of cells, or perhaps earlier in development thus making its identification problematic. Our negative results nevertheless resonate with those from the modENCODE project and a more recent paper by Schmidt and co-workers who performed a transcriptional profiling of diapause and were able to amplify the 12 new cpo isoforms, but not the isoform that is supposed to carry cpo 48034(A/T [30]. Consequently, at this point in time, it would appear that this polymorphism is to be found in non-coding DNA, at least under the conditions that Schmidt et al, modENCODE and ourselves have isolated the corresponding mRNA.…”

The African turquoise killifish: A research organism to study vertebrate aging and diapause

“…Invertebrate systems have also revealed organismal and genetic links between diapause and aging. First, the individuals that undergo diapause in C. elegans or Drosophila resume a normal lifespan when they reach adulthood (Klass & Hirsh, 1976; Kucerova et al., 2016; Zhao et al., 2016). In other documented examples of insects, individuals that have been through diapause significantly even outlive their counterparts that have never entered diapause (Tatar & Yin, 2001).…”

Gene expression clines reveal local adaptation and associated trade-offs at a continental scale

“…Gene expression studies also have been used to explore the molecular mechanisms that may underlie life history trade-offs13141516 because adaptive variation in such quantitative traits may be due to regulatory changes171819. As gene expression is costly20, variation in patterns of gene expression resulting from local adaptation to a thermal gradient may reveal the modifications in resource partitioning involved in adaptive variation in life-history trade-offs21.…”